Radiographic anatomy of knee joint

1. RADIOGRAPHIC ANATOMY OF KNEE
JOINT AND ITS RADIOGRAPHIC
VIEWS
PRESENTATION BY : DR MIRZA SANAULLA
MODERATOR : DR RAGHURAM P

2. OVERVIEW
KNEE JOINT INTRODUCTION
GROSS ANATOMY OF KNEE JOINT
RADIOLOGICAL ANATOMY OF KNEE JOINT
NORMAL VARIANTS
RADIOLOGICAL VIEWS OF KNEE JOINT

3. KNEE JOINT
 Largest joint in human body
 Modified hinge joint – synovial joint
type
 It incorporates two condylar joints
between the condyles of femur and
tibia,and one saddle joint between
femur and patella.
 Flexion and extension of the leg as
well as some rotation in the flexed
position.

4. Patellofemoral Joint
• The patellofemoral compartment is a saddle joint between
the femoral trochlea and patella, formed by a large steeper
lateral facet, resisting patellar lateral displacement, and two
smaller medial facets.

5. Ligaments of knee
joint

6. Bursae of knee joint

7. FATS PADS
 Infrapatellar fat pad (of HOFFA)
 Anterior suprapatellar fat pad
 Posterior suprapatellar (pre-femoral fat
pad)
 Posterior fat pad

8. X-rays of knee
joint
AP VIEW

9. LATERAL VIEW

10. KNEE LATERAL –HORIZONTAL BEAM

11. KNEE LATERAL –HORIZONTAL BEAM

12. NORMAL VARIANTS :
BIPARTITE PATELLA
• 1-3 ossification centres appear at 3 years and
fuse at puberty . These may give rise to an
irregular appearance of the normal unfused
patella. A bipartite(or multipartite) patella is a
common variant when the superolateral corner
fails to fuse.
• The Saupe classification describes the bipartite
patella according to the location of the secondary
ossification center:
type I: inferior pole ~1%
type II: lateral margin ~20-25%
type III: superolateral portion ~75%

13. BIPARTITE PATELLA

14. FABELLA
• The fabella is a
sesamoid bone
frequently found in
the lateral head of
gastrocnemius.

15. RADIOGRAPHIC VIEWS
BASIC PROJECTIONS:
1. ANTERO-POSTERIOR(SUPINE)
2. LATERAL
ADDITIONAL PROJECTIONS:
1.LATERAL –HORIZONTAL BEAM
2.ANTERO-POSTERIOR STANDING
3.STRESS PROJECTIONS-AP
4.POSTERO-ANTERIOR (PATELLA)
5.SKYLINE PROJECTION
6.INTERCONDYLAR NOTCH (TUNNEL)

16. ANTERO-POSTERIOR VIEW (SUPINE)
Direction and location of the X-ray beam
• The vertical collimated central beam is
centred 1 cm below the apex of the patella
through the joint space, with the central ray at
90° to the long axis of the tibia (midway
between the palpable upper borders of the
tibial condyles)

17. AP VIEW (SUPINE)
Essential image characteristics
• The patella must be centralised over
the femur.
• The image should include the proximal
1/3 of the tibia and fibula and distal 1/3
of the femur.

18. LATERAL VIEW
Direction and centring of the X-ray
beam
• Centre to the middle of the superior border of the
medial tibial
condyle, with the central ray at 90 degrees to the long
axis
of the tibia.

19. Essential image characteristics
• The patella should be projected clear of the femur.
• The femoral condyles should be superimposed.
• The proximal tibio-fibular joint is not clearly visible.

20. Insall-Salvati ratio
• The Insall-Salvati ratio or index is the
ratio of the patella tendon length to
the length of the patella and is used
to On plain radiographs:
• Patella baja: <0.8
• Normal : 0.8-1.2
• patella alta : >1.2

21. ANTERO-POSTERIOR (STANDING)
This projection is useful to demonstrate
alignment of the femur and tibia in the
investigation of valgus or varus deformity. Any
such deformity will be accentuated when
weight bearing.
Direction and location of the X-ray beam
 The collimated horizontal beam is centred
1 cm below the apex of the patella through the
joint space, with the central ray at 90° to the
long axis of the tibia (midway between the
palpable upper borders of the tibial condyles).

22. AP VIEW STANDING

23. To enable correct assessment of the joint space, the
central ray must be at 90° to the long axis of the tibia
and, if necessary, angled slightly cranially. If the central
ray is not perpendicular to the long axis of the tibia,
then the anterior and posterior margins of the tibial
plateau will be separated widely and assessment of
the true width of the joint space will be difficult.
 In the AP projection, the patella is remote from the
receptor. Although the relationship of the patella to
the surroundng structures can be assessed, the
trabecular pattern of the femur is superimposed.
Therefore, this projection is not ideal for
demonstrating discrete patella bony abnormalities.

24. LATERAL –HORIZONTAL BEAM (TRAUMA)
This projection replaces the conventional lateral in all cases of
gross injury and suspected fracture of the patella
Direction and location of the X-ray beam
• The collimated horizontal beam is centred to
the upper border of the lateral tibial condyle, at
90° to the long axis of the tibia.
•The femoral condyles should be superimposed
and the soft tissues adequately demonstrated
to visualise any fluid levels within the supra-
patella pouch.

25. LIPOHAEMARTHROSIS

26. Stress projections for subluxation
•Stress projections of the knee joint are taken to show subluxation
due to rupture of the collateral ligaments.
• Stress is applied to the joint by medical personnel.

27. ANTERO-POSTERIOR STRESS PROJECTION
Position of patient and cassette
• The patient and cassette are positioned for the routine
anteroposterior
projection.
• The doctor forcibly abducts or adducts the knee,
withoutrotating the leg.
Direction and centring of the X-ray beam
• Centre midway between the upper borders of the tibial
condyles, with the central ray at 90 degrees to the long
axis of the tibia.

28. POSTERIO-ANTERIOR -
PATELLA
Position of patient and cassette
• The patient lies prone on the table, with the knee slightly
flexed.
• The centre of the cassette is level with the crease of the
knee.
Direction and centring of the X-ray beam
• Centre midway between the upper borders of the tibial
condyles at the level of the crease of the knee, with the
central ray at 90 degrees to the long axis of the tibia.
Notes
• The beam may have to be angled caudally to be at right
angles
to the long axis of the tibia.
• The patella may be demonstrated more clearly as it is
now adjacent to the image receptor and not distant from it,
as in the conventional antero-posterior projection.

29. POSTERO-ANTERIOR VIEW

30. SKYLINE PROJECTION
The skyline projection can be used to:
• assess the retro-patellar joint space for degenerative disease;
• determine the degree of any lateral subluxation of the patella
with ligament laxity;
• diagnose chondromalacia patellae;
• confirm the presence of a vertical patella fracture in acute
trauma.
The optimum retro-patellar joint spacing occurs when the
knee is flexed approximately 30–45 degrees. Further flexion
pulls the patella into the intercondylar notch, reducing the joint
spacing; as flexion increases, the patella tracks over the lateral
femoral condyle. The patella moves a distance of 2 cm from full
extension to full flexion.

31. Supero-inferior view
This projection has the advantage that the radiation beam
is not directed towards the gonads.
Position of patient and cassette
• The patient sits on the X-ray table, with the affected knee
flexed over the side.
Direction and centring of the X-ray beam
• The vertical beam is directed to the posterior aspect of
the proximal border of the patella. The central ray should
be parallel to the long axis of the patella.

32. SKYLINE VIEW –SUPERO INFERIOR
NORMAL SKYLINE VIEW REDUCED FLEXION –CAUSING TIBIA
PROJECTION OVER PATELLA
INCREASED FLEXION –
APPEARS AS LATERAL
SUBLUXATION

33. Infero-superior
Projection
Position of patient and cassette
• The patient sits on the X-ray table, with the knee flexed
30–45 degrees and supported on a pad placed below the knee.
Direction and centring of the X-ray beam
• The tube is lowered. Avoiding the feet, the central ray is
directed cranially 5- 10 degrees to pass through the apex of the
patella parallel to the long axis.

34. Infero-superior – patient prone
This projection has the advantage in that the primary beam is
not directed towards the gonads, as is the case with the
infero-superior projection. However, the patient has to
be able to adopt the prone position, which may not be suitable
for all patients.
Position of patient and cassette
• The patient lies prone on the X-ray table, with the cassette
placed under the knee joint and the knee flexed through 90
degrees.
Direction and centring of the X-ray beam
• Centre behind the patella, with the vertical central ray angled
approximately 15 degrees towards the knee, avoiding the toes

35. INTERCONDYLAR VIEW -TUNNEL VIEW
This projection is taken to demonstrate loose
bodies within the knee joint or to demonstrate
fractures of the tibial spines.
Position of patient and cassette
• The patient is either supine or seated on the
X-ray table, with the affected knee flexed to
approximately 60 degrees.

36. Direction and centring of the X-ray beam
• Centre immediately below the apex of the patella, with
the following angulations to demonstrate either the
anterior or posterior aspects of the notch:
Angulation to the long Anatomy demonstrated
axis of the tibia
110 degrees : Anterior aspect of the notch
90 degrees : Posterior aspect of the notch

37. INTERCONDYLAR NOTCH (TUNNEL) AP VIEW

38. Intercondylar notch (tunnel) – posterior–anterior (racing
start)
The advantage of this method is the reduction in
magnification and increased resolution
The affected lower leg is extended with the tibia parallel
to the tabletop and the patient is asked to lean forwards,
moving the femur into an angle of 50° from the tabletop
Direction and location of the X-ray beam
• The collimated vertical beam is centred to the middle
of the knee joint/popliteal fossa (approximately over the
skin crease posterior to the joint

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